STA-BIL is a blend of additives which prevent fuel from undergoing degradation and oxidation during prolonged storage. It acts as a protective "wrapper" around fuel molecules so they don't combine with oxygen to make fuel go stale. Fuel stabilized with STA-BIL stays fresh and will perform as though it had just been pumped from the refinery pipeline. Typically, the life of gasoline treated with STA-BIL is extended from 2 months to 15 months. USA.